There have been proposed sound image localization apparatuses for processing a sound source signal to localize a sound image at a target position.
JP 2004-193877 A discloses a structure for setting a sound image position, the structure including an X position setting section for setting a longitudinal position on a horizontal plane, a Y position setting section for setting a lateral position on the horizontal plane, a Z position setting section for setting a height position on a vertical plane, a θ position setting section for setting an angle of the horizontal plane, and a φ position setting section for setting an angle of the vertical plane. The listener can set the positions by clicking each item of these setting sections displayed on a graphical user interface (GUI) application screen and sliding a slider.
JP 2008-211834 A discloses a sound image localization apparatus in which a head-related transfer function is implemented.
Jens Blauert, Masayuki Morimoto, and Toshiyuki Goto, “Spatial Hearing”, Kajima Institute Publishing Co., Ltd., Jul. 10, 1986, discloses a technique for localizing a sound image at a desired position by reproducing a head-related transfer function and convolving it with a sound source signal to present the resultant position to the listener.
However, the above-described approach that involves the operation of the X position setting section, the Y position setting section, the Z position setting section, the θ position setting section, and the φ position setting section has a drawback in that it is difficult to image a 3D position of an actual stereoscopic sound image.
As an alternative, there also has been developed binaural recording in which sound is collected using a high-sensitivity microphone attached to a model of a human head at a position behind the eardrum, “a dummy head microphone”; however, this method is generally costly.